Fusion bonded epoxy removal tool

ABSTRACT

A tool for removing fusion bonded epoxy coating from the surface of a pipe has an elongate rotatable shaft suitable for being received in a rotating tool holder of a machine. Extending radially outward of the distal end of the shaft are a plurality of fingers, the outer ends of which are spaced apart. Each of the fingers is made of a spring metal, and at the distal end of each finger is an abrasive pad having diamond particles embedded in soft metal. Spring force is independently applied by each spring finger to its associated abrasive pad.

The applicant claims priority from his provisional application filedOct. 26, 2009 and assigned Ser. No. 61/254,804. The present inventionrelates to tools for removing fusion bonded epoxy from the surface of apipe, and in particular to a disk-shaped tool for removing such fusionbonded epoxy.

BACKGROUND OF THE INVENTION

With the advent of offshore drilling and the transportation of liquidssuch as gas and oil through underwater pipes robotically operatedmachines are needed to repair pipes that extend through deep waters.Such pipes are electrically connected along their length. They also havea coating of fusion bonded epoxy on their outer surface to protect themetal of the pipe from corrosion caused by the chemicals in the ocean.To repair a submerged pipe, the pipe must first be cut in two locationsto remove a defective portion, after which the disconnected ends of theundamaged portions must be prepared to receive a repaired length ofpipe. One of the steps needed to prepare the end of a length of pipe isto remove a portion of the fusion bonded epoxy coating from the outerend of the pipe in order that a good electrical connection may be madethrough the repair length. Also, the manufacturers of the couplings thatattach the repair length to the existing pipe do not guarantee a tightseal unless the fusion bonded epoxy is removed from the repair area.

Currently, the fusion bonded epoxy coating for underwater pipes isremoved by providing a rotating drum, the outer surface of which hasembedded therein hard particles of tungsten carbide. The surface of thedrum is applied to the surface of the pipe and the drum rotated causingthe tungsten carbide particles to remove the fusion bonded epoxy.

It has been found that it is difficult to apply the desired force of thedrum against the outer surface of a pipe having an epoxy surface becauseof the weight of the drum itself. Where the drum is to remove epoxy fromthe upper surface of the pipe, the weight of the drum may exceed theforce desired to be applied to the surface and therefore the machinerotating the drum must compensate for the weight being applied.Conversely, where the drum is rotated against the lower surface of apipe, the machine that rotates the drum must apply a force greater thanthe drum weight against the lower surface of the pipe to overcome theweight of the drum and provide sufficient force to remove the epoxysurface. Similar problems exist where the drum is applied against ahorizontal portion of the pipe. Furthermore, it has been found that thetungsten carbide particles that are embedded in the drum tend to causeexcess damage to the metal of which the pipe is made. Accordingly, thereis a need for an improved tool for removing an epoxy bonded surface froma pipe, especially where the pipe is submerged.

BRIEF DESCRIPTION OF THE INVENTION

Briefly, the present invention is embodied in a tool having an elongaterotatable shaft suitable for being received in a rotating tool holder ofa machine. Extending radially outward of the distal end of the shaft area plurality of fingers, the outer ends of which are spaced apart.

In accordance with the invention, one of the fingers is made of a springmetal, and at the outer end of the finger is an abrasive pad having aplurality of diamond particles embedded therein.

In the preferred embodiment, each of the fingers is made of a springmetal, and at the distal end of each finger is an abrasive pad havingdiamond particles embedded in soft metal. Accordingly, a spring force isindependently applied by each spring finger to its associated abrasivepad.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the invention will be had after a reading ofthe following detailed description taken in conjunction with thedrawings wherein:

FIG. 1 is a side elevational view of a tool in accordance with thepresent invention;

FIG. 2 is a top elevational view of the tool shown in FIG. 1;

FIG. 3 is a bottom view of the tool shown in FIG. 1;

FIG. 4 is a cross-sectional view taken through line 4-4 of FIG. 2; and

FIG. 5 is an exploded view of the tool shown in FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIGS. 1 through 5, a tool in accordance with the presentinvention, a tool 10 is rotatably symmetric about an elongate shaft 12having a rearward end 14 adapted for insertion into the retainer of arotatable machine, not shown, a longitudinal axis 15, and a threadedouter end 16 for threadedly retaining a working end 18. For the purposesof this discussion the working end 18 of the tool 10 shall be consideredthe forward end of the tool 10, and elements described herein that aredirected axially toward the working end 18 shall be considered theforward end thereof and elements that are directed axially toward end 14of shaft 12 shall be considered the rearward end thereof.

The working end 18 is generally disc shaped in appearance and includes acentrally located hub 20 having a planar forward surface 22 and aparallel planar rearward surface 24. Extending rearwardly of therearward surface 24 is a cylindrical projection 26 having opposing flats28, 29. Extending axially through the body of the hub 20 and theprojection 26 is a threaded cylindrical bore 30 sized to threadedlyreceive the forward end 16 of the shaft 12. A hex jam nut 32 is alsothreaded on the forward end 16 of the shaft 12 before the hub 20 forlocking the hub 20 to rotate with the shaft 12. Extending around thecircumference of the hub 20 are planetary parallel threaded bores 34 thecenters of which define a circle that is concentric with the threadedbore 30. In the preferred embodiment, the forward end of the shaft 12does not extend beyond the forward surface 22 of the hub 20.

Positioned adjacent the forward surface 22 of the hub 20 are first andsecond identically shaped star wheels 36, 38, each of which has aplurality of elongate fingers 40. In the embodiment depicted, each starwheel 36, 38 has nine identical fingers 40, however it should beappreciated that the working end 18 of the tool can be made with morefingers or fewer fingers without departing from the spirit and scope ofthe invention. Each star wheel 36, 38 is made of a spring steel andpreferably has a thickness of about one-sixteenth of an inch. Each ofthe star wheels 36, 38 also has a centrally located opening 42 andpositioned around the central opening 42 are a plurality of spaced apartplanetary holes 44 that are equal in number to the threaded bores 34 inthe hub 20. The planetary holes 44 define a circle coaxial with thecentral opening 42 of the star wheel and equal to the diameter of thecircle defined by the planetary holes 34 of the hub 20. The star wheels36, 38 are retained to the forward surface 22 of the hub 20 by aplurality of screws 46-46 sized to be slideably received in the holes 44of the star wheels 36, 38 and threadedly received in the bores 34 of thehub 20. With the star wheels 36, 38 secured to the forward end of thehub 20, the fingers 40 of both star wheels 36, 38 align with one anotherand thereby double the effective spring force provided to each of thestar wheels independently.

At the outer end of each finger 40 of the aligned star wheels 36, 38 area pair of transverse holes 48, 50. Each of the fingers 40 has attachedat its outer end a generally rectangular mounting plate 52 havingthreaded holes 54 therein sized and positioned to receive screws 58-58.The screws 58-58 are fitted through the holes 48, 50 at the distal endof each of the fingers 40 and into the threaded holes 54 of the mountingplates 52 for retaining the mounting plate 52 to the forward surface ofeach of the fingers 40. The mounting plates 52 therefore formed in aplanetary ring on the forward surface of star wheel 38 with eachmounting plate at the distal end of each of the fingers 40.

In accordance with the present invention, each mounting plate 52 hasattached to the forward surface thereof an arcuate shaped diamondcutting segment 60. The diamond cutting segments 60 are preferably madeof a soft metal, such as silver or an alloy thereof with particles ofdiamond material 62 embedded into the soft metal. Each segment 60 issoldered or otherwise secured to the forward surface of one of themounting plates 52. The forward surface of each of the segments 60 cantherefore be applied to the surface of a pipe to remove the fusionbonded epoxy on the outer surface thereof.

A removal tool 10 in accordance with the present invention that has aplurality of independently springed fingers 40 and a diamond cuttingsegment at the distal end of each finger which will independently moveacross the portion of the surface of a coated pipe. The diamondparticles in the various segments 60 provide an abrasive surfacesuitable for removing the fusion bonded epoxy. After each segment hasremoved a portion of the epoxy layer, the spacing between adjacentfingers permits water to circulate around the individual segments 60 andwash accumulated debris from the surface of the segment before rotationagain brings the segment 60 in contact with the surface of the pipe.Also, the provision of independently adjustable fingers 40 allows eachfinger to apply the force desired to remove the epoxy surface from apipe. Furthermore, the spacings between the fingers allow a remotecamera mounted on the machine retaining the tool 10 to view theunderlying pipe between the passage of the successive fingers, such thatan operator can view the operation of the tool without removing the toolfrom the work site. It has also been found that where the segmentsemploy relatively small particles of diamond, the hard cutting materialdoes not unduly damage the outer surface of the pipe as was the casewith a removal tool that employed tungsten carbide inserts.

While the present invention has been described with respect to a singleembodiment, it will be appreciated that many modifications andvariations can be made without departing from the spirit and scope ofthe invention. It is therefore the intent of the appended claims tocover all such modifications and variations that fall within the spiritand scope of the invention.

1-9. (canceled)
 10. A method of removing fusion bonded epoxy coatingfrom a surface of an underwater pipe, the method comprising: submerginga tool underwater adjacent an underwater pipe, wherein the tool includesa plurality of fingers and a plurality of abrasive pads, wherein theplurality of fingers include working ends spaced-apart from each otherand one of the plurality of abrasive pads is coupled to each of theworking ends of the plurality of fingers; engaging a first abrasive padof the plurality of abrasive pads with the underwater pipe; flexing afirst of the plurality of fingers to which the first abrasive pad iscoupled due to the engagement of the first abrasive pad with the pipe;applying a first force to the underwater pipe due to the flexing of thefirst of the plurality of fingers; rotating the tool relative to theunderwater pipe; applying the first abrasive pad against the underwaterpipe, due to rotating, to remove fusion bonded epoxy from the underwaterpipe; engaging a second abrasive pad of the plurality of abrasive padswith the underwater pipe due to rotating the tool; flexing a second ofthe plurality of fingers to which the second abrasive pad is coupled dueto the engagement of the second abrasive pad with the pipe; applying asecond force to the underwater pipe due to the flexing of the second ofthe plurality of fingers; applying the second abrasive pad against theunderwater pipe, due to rotating, to remove fusion bonded epoxy from theunderwater pipe; and circulating water between the first and secondplurality of fingers as a result of rotation of the tool.
 11. The methodof claim 10, wherein rotating the tool further comprises: receiving anelongate shaft of the tool in a tool holder of a machine; securing theelongate shaft to the tool holder; and rotating the tool holder, theelongate shaft, the plurality of fingers, and the plurality of abrasivepads with the machine.
 12. The method of claim 11, wherein: engaging afirst abrasive pad further comprises engaging a first arcuate abrasivepad with the underwater pipe; and engaging the second abrasive padfurther comprises engaging a second arcuate abrasive pad with theunderwater pipe.
 13. The method of claim 12, wherein the first arcuateabrasive pad defines a first arc having a first arc center and a firstradius extending between the first arc center and the first arc, whereinthe second arcuate abrasive pad defines a second arc having a second arccenter and a second radius extending between the second arc center andthe second arc, and wherein rotating further comprises rotating theelongate shaft about a longitudinal axis of the elongate shaft with thefirst and second arc centers displaced from the longitudinal axis. 14.The method of claim 13, wherein the first arc center and the second arccenter are displaced from each other.
 15. The method of claim 11,wherein, prior to rotating, positioning the elongate shaft of the toolsubstantially perpendicular to a central longitudinal axis of theunderwater pipe.
 16. The method of claim 10, wherein engaging a firstabrasive pad further comprises engaging a first arcuate abrasive padwith the underwater pipe, and wherein engaging the second abrasive padfurther comprises engaging a second arcuate abrasive pad with theunderwater pipe.
 17. The method of claim 16, wherein the first arcuateabrasive pad includes a first convex edge and a first concave edge, andwherein the second arcuate abrasive pad includes a second convex edgeand a second concave edge, and wherein engaging a first arcuate abrasivepad further comprises engaging the first convex edge of the firstarcuate abrasive pad with the underwater pipe prior to the first concaveedge, and wherein engaging a second arcuate abrasive pad furthercomprises engaging the second convex edge of the second arcuate abrasivepad with the underwater pipe prior to the second concave edge.
 18. Themethod of claim 10, further comprising viewing the underwater pipe withan underwater camera between the spaced-apart working ends of the firstand second plurality of fingers.
 19. The method of claim 18, furthercomprising coupling the tool to an underwater machine; and coupling theunderwater camera to the machine.
 20. The method of claim 10, furthercomprising fastening the first abrasive pad to the working end of thefirst of the plurality of fingers and fastening the second abrasive padto the working end of the second of the plurality of fingers.
 21. Themethod of claim 20, wherein fastening the first abrasive pad furthercomprises fastening the first abrasive pad to the working end of thefirst of the plurality of fingers with a pair of fasteners.
 22. Themethod of claim 21, wherein fastening the second abrasive pad furthercomprises fastening the second abrasive pad to the working end of thesecond of the plurality of fingers with a pair of fasteners.